EP1505371A1 - Non-contact magnetic position sensor with means for correcting variance among sensor elements - Google Patents

Non-contact magnetic position sensor with means for correcting variance among sensor elements Download PDF

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Publication number
EP1505371A1
EP1505371A1 EP04018365A EP04018365A EP1505371A1 EP 1505371 A1 EP1505371 A1 EP 1505371A1 EP 04018365 A EP04018365 A EP 04018365A EP 04018365 A EP04018365 A EP 04018365A EP 1505371 A1 EP1505371 A1 EP 1505371A1
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Prior art keywords
temperature
angle
sensor
offset
peak
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EP04018365A
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German (de)
English (en)
French (fr)
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Masashi Hitachi Ltd-Intell.Prop.Group Saito
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Hitachi Ltd
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Hitachi Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D3/00—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
    • G01D3/028—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure
    • G01D3/036—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure on measuring arrangements themselves
    • G01D3/0365—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure on measuring arrangements themselves the undesired influence being measured using a separate sensor, which produces an influence related signal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D18/00—Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
    • G01D18/001—Calibrating encoders
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/30—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring angles or tapers; for testing the alignment of axes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/142—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices
    • G01D5/145—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices influenced by the relative movement between the Hall device and magnetic fields
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/244—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
    • G01D5/24471—Error correction
    • G01D5/2448—Correction of gain, threshold, offset or phase control
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/244—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
    • G01D5/24471—Error correction
    • G01D5/24485—Error correction using other sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/244—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
    • G01D5/24471—Error correction
    • G01D5/2449—Error correction using hard-stored calibration data

Definitions

  • the present invention relates to a non-contact position sensor for measuring the rotational angle of a rotator.
  • the temperature of sensor elements is inferred from the entire resistance of the sensor elements, and the output of the sensor elements is corrected on the basis of the inferred temperature.
  • the temperature drift is corrected by a temperature compensating coil serially connected to a sensor coil.
  • the present invention is to provide a non-contact position sensor having improved rotational angle measuring accuracy.
  • Fig. 1 is a whole block diagram of the non-contact position sensor of an embodiment of the present invention.
  • the position sensor of this embodiment measures the rotational angle of a rotator in non-contact.
  • the rotator is, for example, a steering shaft of a car, a handle rod, or a shift rail.
  • a rotating shaft 2 is a shaft joined to the rotator and rotates in synchronization with the rotator or is the rotator itself.
  • a magnet 3 is installed so as to rotate in synchronization with the rotating shaft 2.
  • an angle sensor element 1 provided on a circuit substrate 4 is arranged.
  • a signal processor 5 On the circuit substrate 4, in addition to it, a signal processor 5, a temperature sensor 6, a hall element 7, and a memory 8 are provided.
  • the temperature sensor 6 is arranged close to the sensor element 1 to measure the temperature of the sensor element 1. Further, the hall element 7 is used to decide the angular area and the operation thereof will be described later by referring to Fig. 5. The hall element 7 is arranged close to the angle sensor element 1 to sense the magnetic flux generated by the magnet 3.
  • the signal processor 5 executes a signal process for outputs of the angle sensor element 1, the temperature sensor 6, and the hall element 7 and calculates the angle of the rotating shaft 2.
  • the sensor element 1 is, for example, a giant magnetic resister (GMR) element, or a magnetic resister (MR) element, or an AMR and these elements, depending on the material and manufacturer, differ in the magnetic field necessary for the operation.
  • GMR giant magnetic resister
  • MR magnetic resister
  • AMR AMR
  • KMZ43 magnetic resister
  • the signal processor 5 is, for example, a microcomputer or a PC or DSP board which is externally installed.
  • the circuit substrate 4 is made of, for example, PCB or ceramics or a metal such as SUS. In this case, when a member is arranged between the sensor element 1 and the magnet 3, it must be a non-magnetic substance. In Fig. 1, the circuit substrate 4 is equivalent to a non-magnetic substance.
  • the memory 8 is used for calibration or correction of sensor output which will be described later and uses a RAM, an EPROM, an EEPROM, or a flash memory. It may be included in a microcomputer.
  • the temperature sensor 6 may be any sensor which can provide temperature information of the sensor element 1 and for example, may be considered to be a thermistor. However, for example, as described in Japanese Application Patent Laid-Open Publication No. 2003-021503, the sensor for measuring the resistance of the sensor element may be used as a temperature sensor.
  • Fig. 2 is a block diagram illustrating the circuit configuration of the non-contact position sensor of an embodiment of the present invention. Further, the same numerals as those illustrated in Fig. 1 indicate the same parts.
  • circuit substrate 4 On the circuit substrate 4, in addition to the angle sensor element 1, the temperature sensor 6, the hall element 7, and the signal processor 5, amplifiers 9 and 9A for amplifying outputs of the sensor element 1 and the hall element 7 and a communication IC10 for communicating with the outside device are arranged.
  • the temperature sensor 6 is arranged close to the sensor element 1 to measure accurately the temperature of the sensor element 1. Further, other parts are arranged on the circuit substrate 4, and when there is a heating element among them, the heating element is arranged away from the temperature sensor 6 to prevent the temperature sensor 6 from being affected by the heating element.
  • a heating element an FET switch or an FET driver for rotating the rotating shaft may be considered.
  • Fig. 3 is a waveform diagram of output signals of the angle sensor element of the non-contact position sensor of an embodiment of the present invention.
  • Signals v1 and v2 indicate output signals of the angle sensor element 1 which are amplified to about 30 times by the amplifier 9.
  • the signals v1 and v2 are signals of two systems having mutually 45° phase difference corresponding to the rotational angle of the magnet 3 and both the signal periods are 180°.
  • the signals v1 and v2 of two systems, in an ideal state, are respectively a sine wave and a cosine wave in a period of 180°.
  • the output signal supplied from the angle sensor element 1 is ideally a sine wave or a cosine wave at a period of 180° and the angle can be calculated using an arc-tangent.
  • Fig. 4 is a block diagram of the calibration device used in the non-contact position sensor of an embodiment of the present invention.
  • an angle measuring device 20 and a rotary encoder 30 are mounted on the pedestal. And, the rotating shaft of the angle measuring device 20 and the rotating shaft of the rotary encoder 30 are mounted so as to rotate in synchronization with each other.
  • the angle measuring device 20 and a host computer 40 are connected by CAN communication and transmit and receive data. Further, the output of the rotary encoder 30 is transmitted to the host computer 40 via the angle measuring device 20. In this case, the output of the rotary encoder 30 may be directly connected to the host computer 40.
  • the encoder 30 provides an absolute angle as a standard corresponding to the rotational angle of the rotating shaft.
  • Fig. 5 is a flow chart illustrating the calibration process in the host computer 40.
  • the host computer 40 normalizes the sensor outputs v1 and v2 using Formula
  • Step s20 the host computer 40 divides mutually the normalized signals and calculates the ratios r12 and r21 of v1n and v2n by the following formula (2).
  • r12 v1n/v2n
  • r21 v2n/v1n
  • Fig. 6 is an illustration for the relationship between the rotational angle and the ratio.
  • the host computer 40 divides the angular range for detecting the ratio shown in Fig. 6 into predetermined angle areas. For example, when the angle detection range of the angle measuring device is from 0 to 360°, the host computer 40 divides the angle range into 8 areas according to the following conditions. The respective divided areas have an angular range of about 45°.
  • Vhall1 and Vhall2 when the sensor output is symmetrical with respect to line at a certain angle, are signals used to decide the area.
  • Fig. 7 shows waveform diagrams of the signals Vhall1 and Vhall2.
  • Fig. 7(A) shows the signal Vhall1 and
  • Fig. 7(B) shows the signal Vhall2.
  • the signals Vhall1 and Vhall2 are outputs of the hall element 7 shown in Fig. 1 and are used to detect an angle area exceeding 180°.
  • the signal Vhall1, as shown in Fig. 7(A), is a high-level signal from 90° to 270° and a low-level signal in the other angle areas.
  • the signal Vhall2, as shown in Fig. 7(B), is a high-level signal from 0° to 180° and a low-level signal in the other angle area.
  • the angular range belongs to "Area 1".
  • Fig. 8 is an illustration for the relationship between the shifted angle and r12 and r21. Fig. 8 shows that in each area, the shifted angle uniquely corresponds to either of r12 and r21.
  • Step s50 the relationship between the angle ⁇ and the ratio shown in Fig. 8 is approximated by a cubic function and in each area, coefficients a, b, c, and d for minimizing Formula (3) indicated below are calculated.
  • ⁇ is the shifted angle in each area.
  • x is "ratio - r21" in the area 1, area 3, area 5, and area 7 and "ratio - r12" in the area 2, area 4, area 6, and area 8. Therefore, for example, in the area 1, when the corresponding coefficients a, b, c, and d are obtained, the mapping to the shifted angle in the area 1 from r21 can be obtained.
  • the host computer 40 stores parameters in the memory 8.
  • the parameters to be stored are the parameters used for calibration and calculated parameters.
  • the parameters to be preserved and used are the maximum and minimum values of output 1, the maximum and minimum values of output 2, and temperature information at the time of calibration.
  • the stored and calculated parameters are the coefficients a, b, c, and d in each area and offset angles. Further, the temperature information at the time of calibration is used for correction of the sensor output which will be described later.
  • the amplitude value vpeak is defined as (vmax - vmin)/2 and the offset value voffset is defined as (vmax + vmin)/2.
  • Fig. 9 is a waveform diagram of output signals of the angle sensor element on temperature condition of 125°C.
  • the amplitude v1peak of the sensor have changed as v1peak (25°C) and v1peak(125°C)
  • the v1offset have changed as v1offset (25°C) and v1offset (125°C).
  • the amplitude value v1peak of the sensor outputs decreases and the offset value v1offset have changed.
  • Fig. 10 is a drawing illustrating the relationship between the amplitude value Vpeak and the temperature T.
  • the reaction of the magnetic resister element decreases as the temperature rises, and the magnetic force of the magnet also decreases as the temperature rises, so that the amplitude value of the output shows a tendency to decrease as the temperature rises.
  • the decrease rate depends on the angle sensor elements A1 and A2 and variance between the sensor elements is seen.
  • Fig. 11 is a drawing showing the relationship between the offset value voffset and the temperature T.
  • the offset value voffset does not show the tendency like the amplitude value vpeak.
  • the offset value shows various characteristics such that the offset value increases as the sample temperature rises like the sensor element A3, or the offset value decreases like the sensor element A4 as the sample temperature rises.
  • FIG. 12 is an illustration for explaining changes of the amplitude value v1peak of the sensor element when the sensor element is used at high temperature (for example, 140°C) for many hours.
  • the drawing shows that the amplitude value v1peak decreases as the time T elapses.
  • the cause is mainly thermal demagnetization (irreversible changes) of the magnet.
  • Fig. 13 is a flow chart showing the contents of the first correction method of angle using the non-contact position sensor of an embodiment of the present invention.
  • the first correction method intends to correct all the effects of the following three factors (factors adversely affecting the angle accuracy) on the angle accuracy.
  • ⁇ 1 ⁇ 1 peak (Td) ⁇ f (2 ⁇ ) ⁇ ⁇ 1 + TC ⁇ 1 peak ⁇ (T - Td) ⁇ ⁇ ⁇ 1 + LTD1 peak (time) ⁇ + ⁇ 1 offset (Td) + TC ⁇ 1 offset ⁇ (T - Td)
  • v2 ⁇ 2 peak (Td) ⁇ g(2 ⁇ ) ⁇ ⁇ 1 + TC ⁇ 2 peak ⁇ (T - Td) ⁇ ⁇ ⁇ 1 + LTD2 peak (time) ⁇ + ⁇ 2 offset (Td) + TC ⁇ 2 offset ⁇ (T - Td)
  • v1peak is a peak voltage of the output v1
  • v2peak is a peak voltage of the output v2
  • f and g are normalized functions of ⁇ having a center value of 0 and an amplitude of ⁇ 1
  • Td is a temperature at the time of calibration
  • T is an optional temperature
  • ⁇ is a rotation angle
  • TCv1peak is a temperature coefficient of the peak voltage v1peak.
  • TCv2peak a temperature coefficient of the peak voltage v2peak
  • LTD1peak is a deterioration coefficient of the peak voltage v1peak due to time
  • LTD2peak is a deterioration coefficient of the peak voltage v2peak due to time
  • v1offset is an offset voltage of the output v1
  • TCv1offset is a temperature coefficient of the offset voltage v1offset
  • v2offset is an offset voltage of the output v2
  • TCv2offset is a temperature coefficient of the offset voltage v2offset
  • time is an elapsed time when the time of calibration is put into the initial state.
  • the peak voltage v1peak, the peak voltage v2peak, the temperature coefficient TCv1peak of the peak voltage v1, the temperature coefficient TCv2peak of the peak voltage v2, the temperature coefficient TCv1offset of the offset voltage, and the temperature coefficient TCv2offset of the offset voltage are functions of temperature and the deterioration coefficients due to time LTD1peak and LTD2peak are functions of time.
  • ⁇ 1 calibration ⁇ 1 peak (Td) ⁇ f (2 ⁇ ) + ⁇ 1 offset (Td)
  • ⁇ 2 calibration ⁇ 2 peak (Td) ⁇ g(2 ⁇ ) + ⁇ 2 offset (Td)
  • Step s100 the calibration in the initial state shown in Fig. 5 is performed.
  • Step s110 on two different temperature conditions, the rotating shaft of the angle measuring device is rotated and the output of the angle measuring device at that time is detected.
  • Step s120 the maximum values v1max and v2max of the sensor output, and the minimum values v1min and v2min are measured.
  • Step s130 from the maximum values and minimum values obtained at Step s120, the temperature characteristics TCv1peak and TCv2peak of the amplitude value, and the temperature characteristics TCv1offset and TCv2offset of the offset value are measured.
  • ⁇ 1 peak (Td) ⁇ 1 max (Td) - ⁇ 1 min (Td) 2
  • ⁇ 1 peak (T1) ⁇ 1 max (T1) - ⁇ 1 min (T1) 2
  • TC ⁇ 1 peak ⁇ 1 peak (T1) - ⁇ 1 peak (Td) ⁇ 1 peak (Td) ⁇ (T1 - Td)
  • the offset value v1offset (T1) at the temperature T1 of the output v1 is obtained by Formula (17) indicated below.
  • ⁇ 1 offset (T1) ⁇ 1 max (T1) + ⁇ 1 min (T1) 2
  • TC ⁇ 1 offset ⁇ 1 offset (T1) - ⁇ 1 offset (Td) ⁇ 1 offset (Td) ⁇ (T1 - Td)
  • TC ⁇ 2peak ⁇ 2 peak (T1) - ⁇ 2 peak (Td) ⁇ 2 peak (Td) ⁇ (T1 - Td)
  • TC ⁇ 2 offset ⁇ 2 offset (T1) - ⁇ 2 offset (Td) ⁇ 2 offset (Td) ⁇ (T1 - Td)
  • the temperature coefficients TCv1peak, TCv2peak, TCv1offset, and TCv2offset obtained at Step s130 are stored in the memory 8. Furthermore, by the temperature sensor, the temperature T of the sensor element can be measured at an optional time.
  • the signal processor 5 calculates Formulas (21) and (22) indicated below from the temperature coefficients TCv1peak, TCv2peak, TCv1offset, and TCv2offset stored in the memory, the output T of the temperature sensor, the sensor outputs v1 and v2, and the temperature information Td at the time of calibration, thus performs correction calculations.
  • the signal processor 5 calculates the ratios by the following process. Namely, firstly, the signal processor 5 does division of Formulas (21) and (22) and calculates the ratios, thus Formula (23) or (24) indicated below is obtained.
  • Formulas (23) and (24) are recalculated respectively using Formula (25), Formulas (26) and (27) are obtained.
  • Step s170 the corrected ratios r12calibration and r21calibration obtained by Formulas (26) and (27) are substituted for x of Formula (3) and the angle ⁇ is calculated.
  • the output on an optional temperature condition or after an optional lapse of time is corrected and the angle can be calculated with high accuracy.
  • Fig. 14 shows an angle deviation when the angle is calculated from the sensor output without being corrected.
  • Fig. 15 shows an angle deviation when the angle is calculated from the sensor output by the aforementioned correction.
  • the angle deviation is "the absolute angle - the calculated angle”.
  • Fig. 16 shows the relationship between the temperature and the angle deviation (maximum value and minimum value).
  • a line B1 shows the maximum deviation when the angle is not corrected and a line B2 shows the minimum deviation when the angle is not corrected.
  • a line C1 shows the maximum deviation when the angle is corrected and a line C2 shows the minimum deviation when the angle is corrected.
  • the calibration is executed at normal temperature (about 25°C), so that when the angle is calculated without being corrected, the angle deviation increases as the temperature rises from the normal temperature. For example, assuming the operation temperature of the angle measuring device as - 40°C to 125°C, the maximum deviation is recorded at 125°C. However, as shown in Fig. 17. it is found that when the correction is performed, the angle detection accuracy is improved.
  • the second correction method is effective when several target angles are decided at predetermined mutually discontinuous positions beforehand.
  • four target angles PosA (345° to 5°), PosB (70° to 80°).
  • PosC 165° to 175°
  • PosD 260° to 270°
  • the angle measuring device is applied to a shift controller for two-wheel drive - four-wheel drive switching.
  • the shift controller detects the four positions of two-wheel drive, four-wheel drive high, four-wheel drive low, and neutral and switches to the drive mechanism corresponding to each of the four positions.
  • the target angles PosA to PosD correspond to the four positions.
  • the target position is set to a certain position, for example, PosA. Since the target angle is set to PosA, the rotating shaft is stopped at the position of PosA and a predetermined sensor output is outputted according to Fig. 18. After the temperature is changed (T2), when the target angle is switched from PosA to PosB by an external signal, the rotating shaft is rotated toward the position of PosB. During this period, the temperature is changed, so that furthermore, a case that the sensor output is changed by variance due to time may be considered, and the angle accuracy is affected by output changes.
  • the relative angle between the sensor element and the magnet is set beforehand so as to pass the peak value of the sensor output.
  • the aforementioned error factor can be corrected. Namely, as shown in Fig. 18, at ⁇ 1, the output 2 indicates a maximum value of v2max and at ⁇ 2, the output 1 indicates a maximum value of v1max.
  • the phase difference between the outputs v1 and v2 is 45°, so that the moment the output 1 records the maximum value, the output 2 indicates the offset value v2offset. Further, similarly, the moment the output 2 records the maximum value, the output 1 indicates the offset value v1offset.
  • the angle can be corrected only by the temperature coefficient of the offset value.
  • Step s200 shown in Fig. 17 the calibration in the initial state shown in Fig. 5 is performed.
  • Step s210 the rotating shaft is rotated. Namely, so as to move from the target angle PosA shown in Fig. 18 to PosB and pass halfway the angles ⁇ 1 and ⁇ 2, the rotating shaft is rotated.
  • Step s220 at the angle ⁇ 1, the maximum value v2max of the sensor output and the minimum value v1offset of the offset value are detected and at the angle ⁇ 2, the maximum value v1max of the sensor output and the minimum value v2offset of the offset value are detected.
  • Step s230 from the maximum value and minimum value obtained at Step s120, the temperature characteristics TCv1offset and TCv2offset of the offset value are measured.
  • the signal processor from the data recorded in the memory at the time of calibration beforehand, can recognize the offset voltages (v1offset (Td), v2offset (Td)) at the time of calibration (temperature Td). Further, since the temperature (T2) during operation can be measured by the temperature sensor, the temperature coefficients TCv1offset and TCv2offset of the offset value can be calculated from Formulas (28) and (29) indicated below.
  • TC ⁇ 1 offset ( ⁇ 1 offset (T2) - ⁇ 1 offset (Td)) (T2 - Td)
  • TC ⁇ 2 offset ( ⁇ 2 offset (T2) - ⁇ 2 offset (Td)) (T2 - Td)
  • Step s240 the correction calculation is performed.
  • the signal processor calculates the ratios by the following process. Namely, firstly, the signal processor does division of Formulas (32) and (33) and calculates the ratios, thus Formula (34) or (35) indicated below is obtained.
  • Step s260 the corrected ratios r12calibration and r21calibration obtained by Formulas (34) and (35) are substituted for x of Formula (3) and the angle ⁇ is calculated.
  • This correction method corrects only the temperature characteristics of the amplitude value. For example, when a magnet (for example, HB-081 material by Hitachi Kinzoku) having little variance due to time caused by heat is adopted, the variance. coefficients TCv1peak and TCv2peak due to time of the amplitude value can be ignored. Further, when an operational amplifier of a low offset drift (for example, LT1050 by Linear Technology) is adopted as an amplifier, the temperature characteristics TCv1offset and TCv2offset of the offset value can be ignored.
  • a magnet for example, HB-081 material by Hitachi Kinzoku
  • coefficients TCv1peak and TCv2peak due to time of the amplitude value can be ignored.
  • an operational amplifier of a low offset drift for example, LT1050 by Linear Technology
  • Step s300 shown in Fig. 19 the calibration in the initial state shown in Fig. 5 is performed.
  • Step s310 the rotating shaft is stopped.
  • Step s320 the sensor outputs v1 (T1) and v2 (T1) at the temperature T1 are detected.
  • Step s330 the sensor outputs v1 (T2) and v2 (T2) at the temperature T2 are detected.
  • Step s340 from the sensor outputs obtained at Steps s320 and s330, the temperature characteristics TCv1peak and TCv2peak of the amplitude are obtained.
  • TC ⁇ 1 peak ⁇ 1(T1) - ⁇ 1(T2) ( ⁇ 1(T2) - ⁇ 1 offset (Td)) ⁇ (T1 - Td) - ( ⁇ (T1) - ⁇ 1 offset (Td)) ⁇ (T2 - Td)
  • TC ⁇ 2 peak ⁇ 2(T1) - ⁇ 2(T2) ( ⁇ 2(T2) - ⁇ 2 offset (Td)) ⁇ (T2- Td) - ( ⁇ (T2) - ⁇ 2 offset (Td))
  • Step s350 the temperature characteristics of the amplitude value are stored in the memory 8.
  • Step s360 the correction calculation is performed.
  • Formulas (36) and (37) are deformed using the sensor outputs v1 and v2, the offset voltages v1offset (Td) and v2offset (Td) at the time of calibration (temperature Td), and the temperature coefficients TCv1peak and TCv2peak of the amplitude value stored in the memory, Formulas (40) and (41) indicated below are obtained.
  • the signal processor calculates the ratios by the following process. Namely, firstly, the signal processor does division of Formulas (40) and (41) and calculates the ratios, thus Formula (42) or (43) indicated below is obtained.
  • Step s370 the corrected ratios r12calibration and r21calibration obtained by Formulas (42) and (43) are substituted for x of Formula (3) and the angle ⁇ is calculated.
  • the temperature characteristics of the amplitude value are corrected and the angle can be calculated with high accuracy.
  • the angle deviation is reduced, thus the angle detection accuracy can be improved.
  • the rotational angle measuring accuracy can be improved.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
EP04018365A 2003-08-05 2004-08-03 Non-contact magnetic position sensor with means for correcting variance among sensor elements Withdrawn EP1505371A1 (en)

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JP2003286400 2003-08-05
JP2003286400A JP4044880B2 (ja) 2003-08-05 2003-08-05 非接触式角度測定装置

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FR2927700A1 (fr) * 2008-02-18 2009-08-21 Continental Automotive France Procede d'etalonnage d'un capteur de mesure
WO2011131449A1 (de) * 2010-04-20 2011-10-27 Dr. Johannes Heidenhain Gmbh Baueinheit für eine winkelmesseinrichtung
US20140025330A1 (en) * 2012-07-11 2014-01-23 Mcube, Inc. Dynamic temperature calibration
CN104949611A (zh) * 2014-03-31 2015-09-30 阿自倍尔株式会社 角度传感器的温度补偿装置
US9500724B2 (en) 2012-11-14 2016-11-22 Portescap Sa Magnetic encoder
EP3460411A1 (de) * 2017-09-20 2019-03-27 Bernstein AG Magnetempfindliche sensoreinheit und deren verwendung
EP3450907A4 (en) * 2016-04-28 2019-07-24 Mitsubishi Electric Corporation ANGLE DETECTION DEVICE AND ELECTRIC POWER STEERING DEVICE
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WO2009103419A1 (fr) * 2008-02-18 2009-08-27 Continental Automotive France Procédé d'étalonnage d'un capteur de mesure
US8370099B2 (en) 2008-02-18 2013-02-05 Continental Automotive France Method of calibrating a measurement sensor
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US20140025330A1 (en) * 2012-07-11 2014-01-23 Mcube, Inc. Dynamic temperature calibration
US9500724B2 (en) 2012-11-14 2016-11-22 Portescap Sa Magnetic encoder
CN104949611A (zh) * 2014-03-31 2015-09-30 阿自倍尔株式会社 角度传感器的温度补偿装置
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US9804006B2 (en) 2014-03-31 2017-10-31 Azbil Corporation Angle sensor temperature correcting device
EP3450907A4 (en) * 2016-04-28 2019-07-24 Mitsubishi Electric Corporation ANGLE DETECTION DEVICE AND ELECTRIC POWER STEERING DEVICE
EP3460411A1 (de) * 2017-09-20 2019-03-27 Bernstein AG Magnetempfindliche sensoreinheit und deren verwendung
EP3503379A4 (en) * 2017-11-02 2020-07-08 Igarashi Electric Works Ltd. CONTROL DEVICE OF A DC MOTOR

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KR20050016122A (ko) 2005-02-21
JP4044880B2 (ja) 2008-02-06

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